The scalb() function computes x * rⁿ, where r is the radix of the machine's floating point arithmetic. When r is 2, scalb() is equivalent to ldexp(3C).

Upon successful completion, the scalb() function returns x * rⁿ.

If the correct value would overflow, scalb() returns +-HUGE_VAL (according to the sign of x) and sets errno to ERANGE.

If the correct value would underflow to 0.0, scalb() returns 0 and sets errno to ERANGE.

The scalb() function returns x when x is +-Inf.

If x or n is NaN, then scalb() returns NaN.

For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by Standards other than XPG4.

The scalb() function will fail if:

ERANGE

The correct value would overflow or underflow.

An application wishing to check for error situations should set errno to 0 before calling scalb(). If errno is non-zero on return, or the return value is NaN, an error has occurred.

See attributes(5) for descriptions of the following attributes:

ldexp(3C), matherr(3M), attributes(5)